Yukito Furukawa

Construction and Commissioning of A 248 m‐long Beamline with X‐ray Undulator Light Source

A medium‐length beamline with undulator source, BL20XU at SPring‐8, was constructed, and opened to public use. The distance from source point to the end of the beamline is 248 m. By utilizing the long beam transport path, the beamline has advantages for experiment that requires high spatial coherence in hard X‐ray regions.

Construction and Commissioning of BL37XU at SPring-8

Trace element analysis beamline (BL37XU) at SPring‐8 was designed for application to various X‐ray fluorescence analyses such as XRF imaging, XAFS, TXRF and XRF holography. The beamline has of two branches, one being a SPring‐8 standard undulator‐beamline optics branch (Branch A) and the other a high‐energy branch (Branch B). In the experimental hutches, several kinds of experimental device are equipped. The end‐stations have been opened to public use since November 2002, and various experiments have been carried out.

Performance of a Highly Stabilized and High-resolution Beamline BL17SU for Advanced Soft X-ray Spectroscopy at SPring-8

A new soft x‐ray beamline BL17SU (RIKEN) has been constructed at SPring‐8. The beamline consists of two branches with each varied‐line‐spacing‐plane‐grating‐monochromator. Both monochromators perform high energy resolution (E/ΔE > 10,000) between 0.2 and 1 keV. One of the monochromator achieves high energy stability of 10 meV over a period of half a day.

SPring-8 standard x-ray monochromators

Most SPring-8 x-ray beamlines are installed double-crystal monochromators that are standardized. For x-ray undulator beamlines where power density of the beam are quite high, rotated-inclined double-crystal geometry is usually adopted, which enlarges the footprint of the incident beam on the crystal surface to reduce the power density. On the other hand, adjustable-inclined double-crystal geometry is adopted for bending-magnet beamlines to extend the available energy range with a limited Bragg angle range. The standardized monochromator mechanism is compatible to both of the geometries, only by changing crystal mounts. Detailed description of the monochromator mechanism is presented.

New soft X-ray beamline BL07LSU at SPring-8

The design and performance of a new soft X-ray beamline BL07LSU at SPring-8 are described. The combination of a novel segmented cross undulator and beamline monochromator has achieved high energy resolution (E/ΔE > 10000) and high photon flux [>1012 photons s−1 (0.01% bandwidth)−1] in the photon energy range 250–2000 eV with fully controllable polarization.

Data acquisition system for X-ray free-electron laser experiments at SACLA

We have developed a data acquisition, control, and storage system for user experiments at the X-ray Free Electron Laser facility, SACLA, at the SPring-S site. The system is designed to handle up to 5 Gbps data rate of shot-by-shot data in synchronization with the 60-Hz of beam repetition cycle. The system has been stably operating for the public users experiments since March 2012.

Stable top-up operation at SPring-8

Top-up operation allows SPring-8 to provide highly stable X-ray beams with arbitrary filling patterns. The implementation of top-up operation is described, with a focus on the simultaneous achievement of stability of stored current, beam orbit, purity of an isolated single bunch, and beam injection efficiency. Stored-current fluctuations have been routinely reduced to a level of 10(-3). Stored-beam oscillation on frequent beam injection, which was originally regarded as the most serious problem, has been successfully suppressed to a sufficiently low level that it never perturbs imaging experiments. Current impurities in nominally empty buckets have been reduced to a level of 10(-9) over more than one week of operation, making possible the measurement of time-resolved spectra using high-current bunches. Finally, excellent injection efficiency, higher than 80%, is routinely obtained, even for small undulator gaps, which is critical for preventing radiation damage to insertion-device magnets and to reduce leakage radiation. The process of achieving highly stabilized top-up operation at SPring-8 and its utility for user experiments are described.

Fixed-height exit bender of synchrotron X-rays above 40 keV

A crystal bender for sagittal focusing has been designed for standard monochromators at SPring-8. The bender does not move the position of the crystal center when the bending radius is changed. Sagittal focusing from 40 keV to 60 keV was achieved by using Si(311) double crystals. The flux density of the focused beam measured at 40 keV was 15 times higher than that of the unfocused beam. The height deviation of the focused beam throughout the measured energy range was within +/- 0.15 mm.

Degree of circular polarization of soft X-rays emitted from a multi-polarization-mode undulator characterized by means of magnetic circular dichroism measurements.

The degree of circular polarization of soft X-rays emitted from the multi-polarization-mode undulator of BL17SU at SPring-8 has been deduced by means of magnetic circular dichroism in core-level X-ray absorption spectroscopy for a ferrimagnetic Gd-Fe-Co amorphous thin film. The results of reference measurements performed using well characterized undulator radiation of BL25SU at SPring-8 have also been utilized. The degrees of circular polarization were presumed for all the available operational modes and were compared with simple theoretical calculations. It was found that the calculated degrees of circular polarization were validated by the measurements reasonably well and will be useful in further experiments at BL17SU.

Standard Transport Channels of X-ray Beamlines at SPring-8

SPring-8 is constructing most of its beamlines using a combination of standardized components. The structures of the beamlines are also standardized according to the light-source characteristics. Specifications of components as well as the unified method of assembly and alignment are described.